I doubt it's the computer's fault if it used to work before and it has happened to so many of them (vista, windows 7, etc).
I didn't have the patience to wait so I showered and ate while it was patching, that lasted about an hour or so; still looping. Someone else tried patching and waited for like, 3 hours, and still looping.
If you're reading this, I'm currently playing @ Grand Chase Reborn
IGN: Eucleides | Feel free to join and add me!